1. Field of the Invention
The present invention relates to a monoclonal antibody specific to human pancreatic phospholipase A.sub.2, its production, a hybridoma for producing it and an assay of human pancreatic phospholipase A.sub.2 using it.
2. Discussion of Prior Art
Phospholipase A.sub.2 (hereinafter referred to as PLA.sub.2) is an enzyme hydrolyzing diacylglycerophospholipid in an ester linkage at the second position. PLA.sub.2 is roughly classified into intracellular or membraneous PLA.sub.2 and PLA.sub.2 secreted from the pancreas as a digestive enzyme. The latter is produced as prophospholipase A.sub.2 in the pancreatic acinar cell and secreted into pancreatic duct. Then it is hydrolyzed mainly by trypsin in the duodenum to cleave the amino terminal peptide chain comprising 7 amino acid residues to give active PLA.sub.2. Isolation of human pancreatic PLA.sub.2 from the pancreas and pancreatic juice has previously been reported (Magee, W. L. et al, Biochem. J. 83, 17-25, 1962; Grataroli, R. et al, Biochimie 63, 677-684, 1981; Nishijima, J. et al, J. Biochem., 94, 137-147, 1983 and so on).
It has been reported that in pancreatitis the blood level of pancreatic PLA.sub.2 is elevated. Accordingly, the assay of pancreatic PLA.sub.2 can be utilized in diagnosing acute abdominal diseases including acute pancreatitis.
Hitherto, pancreatic PLA.sub.2 in serum has been assayed the enzymatically. However, enzymatic activity of pancreatic PLA.sub.2 in the serum is low and, therefore, the assay requires a long and complicated procedure, which makes it practically impossible to clinically apply the assay for the diagnosis of an acute abdomen.
As an immunoassay of pancreatic PLA.sub.2, the radioimmunoassay by Nishijima et al (J. Biochem. 94, 137-147, 1983) and the fluoroimmunoassay by Eskola et al (Clin. Chem. 29, 1777, 1983) have already been reported. According to both methods, the blood level of PLA.sub.2 in acute pancreatitis is higher than the normal level. This fact suggests that the immunoassay can be applied for diagnosing acute abdomen including acute pancreatitis.
As described above, human pancreatic PLA.sub.2 has been able to be assayed immunologically in some instances. However, the antibodies used in the above reports are polyclonal antibodies (rabbit antiserum). A polyclonal antibody is inferior to a monoclonal antibody in terms of specificity, equality and stable supply. Moreover, if a monoclonal antibody having a high affinity is obtained, it becomes possible to develop a more simple and quick assay method for human pancreatic PLA.sub.2.